The goal of this project is to investigate the Bezold-Brucke effect using the psychophysical methods of magnitude estimation and forced choice hue judgments under varying conditions of simultaneous and successive chromatic contrast. In some experiments, unique hues will be determined using the methods of Larimer, Krantz, and Cicerone (1973 a,b), in others the hue scaling technique of Jameson and Hurvich (1959) will be used, and in a third set of studies direct magnitude estimates of redness/greenness and yellowness/blueness will be employed. The theoretical framework is that of the hering, Hurvich, and Jameson opponent-colors theory. Particular emphasis will be placed on what Krantz (1973 a,b) calls Grassmann codes and invariant codes as models for cancellation codes and magnitude codes, respectively.